Engine Running Behavior - Stihl BT 120 C Instruction Manual

English / USA
If engine is down on power, difficult to
start or runs poorly at idling speed, first
check the spark plug.
:
Remove spark plug as described
in chapter "Starting / Stopping the
Engine".
:
Clean dirty spark plug.
: Check the electrode gap (A) and
readjust if necessary – see
"Specifications".
: Use only resistor type spark plugs
of the approved range.
Rectify problems which have caused
fouling of spark plug:
: Too much oil in fuel mix.
: Dirty air filter.
:
Unfavorable running conditions,
e.g. operating at part load.
Fit a new spark plug after approx.
100 operating hours
or earlier if the electrodes are badly
eroded.
22
1
To reduce the risk of fire and burn
injury, use only spark plugs
authorized by STIHL. Always press
spark plug boot (2) snugly onto
terminal (1) of the proper size.
(Note: If terminal has detachable
SAE adapter nut, it must be
attached.) A loose connection
between spark plug boot and
ignition wire connector in the boot
may create arcing that could ignite
combustible fumes and cause a fire.

Engine Running Behavior

If engine running behavior is
unsatisfactory even though the air filter
is clean and the carburetor properly
adjusted, the cause may be in the
muffler.
2
Have the muffler checked for
contamination (coking) by a STIHL
dealer.
BT 120 C